(In reply to comment #4)
> Can you bisect?

Apparently, this is the bad commit:

39737e17e7a61535a35669756161005a7a5c887b is the first bad commit
commit 39737e17e7a61535a35669756161005a7a5c887b
Author: Marek Olšák <maraeo@gmail.com>
Date:   Mon Dec 3 01:26:22 2012 +0100

    st/dri: always allocate private depth-stencil buffers

    This disables DRI2 sharing of zbuffers. The window zbuffer is allocated
just
    like any other texture - through resource_create.

    The idea of allocating a zbuffer through DRI2 isn't very useful with MSAA,
    where a single-sample zbuffer is useless.

    IIRC, the Intel driver does the same thing.

    Reviewed-by: Brian Paul <brianp@vmware.com>

:040000 040000 e8045e2d2c7e9a1ebd6eb1f22c93b97b9c3e8ce7
4deb5755e011d592366e6140bf385bfefe157f3f M    src